EP 1514966A1 provides numerous seal assembly solutions for preventing water leakage from the tub at the through seat for the drive shaft of the drum, and for protecting the bearings of the drum shaft. In all these solutions, the sealing assemblies have one or more sealing lips, and provide for exclusively radial sealing directly on the drum drive shaft. In some embodiments, one of the sealing lips is loaded by a toroidal spring for increasing the radial pressure exerted by the lip; and, in all cases, the seal assembly must be protected at least partly against contact with the wash fluid, on the side facing the tub, by a rigid plastic shield which does not cooperate with any of the sealing lips.
The sealing assemblies illustrated in EP 1514966A1, and described briefly above, have numerous drawbacks. Firstly, friction is severe, on account of the relatively high contact pressure exerted by the sealing lips, especially when spring-loaded, thus resulting in high energy consumption of the appliance, and, above all, in rapid wear of the sealing lips. Secondly, the seal assembly and protective shield are relatively bulky. And, lastly, in an operating environment such as the connection between the tub and drum of a washing machine—characterized by severe vibration, frequent inversion of the rotation direction of the drum, and widely varying rotation speeds (from a few rpm during the wash cycles to over 1000 rpm during the spin cycle)—the seal assemblies described are extremely noisy.